| 摘要 |
There is provided a method of controlling a converter including at least one converter limb corresponding to a or a respective phase of the converter, the or each converter limb extending between first and second DC terminals and including first and second limb portions separated by an AC terminal, each limb portion including a converter arm, at least one of the limb portions including at least one director arm, the or each director arm including a director switch, the or each director switch being switchable to selectively permit and inhibit a flow of current in the corresponding director arm. The method comprises the steps of:
(a) obtaining a or a respective AC current demand phase waveform for the or each converter limb which the corresponding converter limb is required to track, and a DC current demand which the or each converter limb is also required to track;
(b) determining a limb portion current (I A+ , I A- ) for each limb portion that the limb portion must contribute to track the corresponding required AC current demand phase waveform and the required DC current demand, wherein the step of determining the limb portion current for each limb portion includes determining a director arm current for the or each director arm that the director arm must contribute to track the corresponding required AC current demand phase waveform and the required DC current demand, wherein the step of determining the limb portion current for each limb portion includes determining a converter arm current for each converter arm that the converter arm must contribute to track the corresponding required AC current demand phase waveform and the required DC current demand, wherein each of the determined arm currents (I A+ , I A- ) includes a current ramp profile (100,102), each of the current ramp profiles (100,102) including a non-zero current slope;
(c) timing the current ramp profile (100) of the determined director arm current (I A+ ) for the director arm or the one of the director arms to fully or partially overlap with the current ramp profile (102) of the determined arm current (I A- ) for the one of the other arms so as to cause transfer of current between the director arm or the one of the director arms and the one of the other arms:
before the director switch for the director arm or the one of the director arms is switched from permitting a flow of current to inhibiting a flow of current in the corresponding director arm; and/or
after the director switch for the director arm or the one of the director arms is switched from inhibiting a flow of current to permitting a flow of current in the corresponding director arm; and
(d) providing a limb portion voltage source for each limb portion to achieve the corresponding determined limb portion current (I A+ , I A- ). |
